The present invention relates to a method for the electrolytic etching of a metal workpiece and more particularly to a method for the electrolytic etching of a metal workpiece wherein a stencil of an electric insulating material is applied on a metal workpiece and the metal workpiece with the stencil is set as an anode opposite to a cathode and a jet of electrolyte is introduced between the cathode and the metal workpiece so that the metal workpiece is electrolytically etched and then the above mentioned steps are repeated using the same stencil, until many metal workpieces are etched.
Electrochemical method and chemical methods are already known among methods for etching a metal workpiece.
The following three methods are enumerated as the method for the electrochemical etching of a metal workpiece.
(1) A method wherein a metal workpiece provided with an electric insulating resist pattern on the surface is set in an electrolyte opposite to the cathode of an insoluble metal so that only the bare part of the above mentioned metal workpiece may be electrolytically etched;
(2) A so-called electochemical machining method wherein a tool electrode is placed approaching a metal workpiece as an anode while an electrolyte is jetted on the metal workpiece from a jet of the tool electrode, and during the etching process the tool electrode is gradually traveled toward the metal workpiece while the distance there between is kept constant so that the metal workpiece is electrolytically machined in the configuration following exactly the configuration of the electrode; and
(3) A method known as an electrolytic marking method wherein a stencil is wet with an electrolyte and is then applied on a metal workpiece, and a cathode is placed into contact with said stencil and an electric current is passed through the electrolyte in the direction from the metal workpiece to the cathode so that the metal workpiece is electrolytically etched to a minute depth.
As the first method for etching a metal by using a resist, there is practiced a method wherein a resist pattern is formed by printing a resist ink on a metal workpiece and subsequent drying or a method wherein a resist pattern is formed by painting a photoresist on a metal workpiece, with drying, exposing the photoresist through a master plate, developing the photoresist, and drying.
In the electrolytic etching by forming a pattern of a resist, there is required an operation consisting of nine steps of (1) a pretreatment of the metal workpiece, (2) drying, (3) printing of resist ink, (4) drying, (5) electrolytic etching, (6) water washing, (7) resist removal, (8) washing and (9) drying.
Also, in the electrolytic etching by forming a pattern of a photoresist, there is required an operation consisting of 13 steps of (1) a pretreatment of the metal workpiece, (2) drying, (3) photoresist painting, (4) drying, (5) exposing through a master pattern, (6) developing, (7) drying, (8) baking, (9) electrolytic etching, (10) water washing, (11) photoresist removal, (12) washing and (13) drying.
Thus, in such methods for the etching of a metal workpiece by using a resist, it is necessary to form a resist ink or photoresist for each etching of a metal workpiece and, in addition, there are many operation steps which are complicated and increase cost.
Also, in the second electrochemical machining method, there exists the problems that the tool electrode is costly and the complicated form is difficult to work.
In the third electrolytic marking method, the electrolyte is consumed instantaneously, the sludge accumulates and therefore the etching can not be deeply performed.
Further, as the latter chemical etching method, there is known a chemical milling method wherein a pattern called a masking plate which is made of a soft and anticorrosive material such as a rubber, is used, and a metal workpiece is clamped between said pattern and an anticorrosive base plate in order that the non-etched part is protected.
In this method, many metal workpieces can be repeatedly etched with one masking plate and therefore there is an advantage that a metal workpiece can be efficiently etched at a low cost. On the other hand, there are defects in that this method has limited application to a simple-shaped product, and can not be applied to a complicated-shaped product or to a product having an isolated pattern in the form of an island, and can not be applied to a product having a large area and where machining tolerance is very low.
An object of the present invention is to provide a method for the electrolytic etching of a metal workpiece wherein there are no defects of conventional metal etching methods and etched products having a close tolerance can be simply and quickly produced at a low cost in a comparatively few operating steps.
Another object of the present invention is to provide a method for the electrolytic etching of metal workpiece wherein a metal workpiece of a large area can be accurately etched.
Other objects and further scope of applicability of the present invention will become apparent from the detailed description given hereinafter; it should be understood, however, that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.
The present invention is directed to a method for the electrolytic etching of a metal workpiece comprising placing a stencil made of an electric insulating material having a pattern consisting of opening parts and non-opening parts into intimate contact with a metal workpiece, opposing an electrode to said metal workpiece, jetting an electrolyte between said metal workpiece and electrode while passing an electric current through the jet of electrolyte in the direction of from the metal workpiece to the electrode to electrolytically etch said metal workpiece, then separating said stencil from the electrolytically etched metal workpiece, placing it into intimate contact with the next metal to be electrolytically etched, electrolytically etching the metal workpiece in the same manner as is mentioned above and then repeating the latter electrolytic etching with said one stencil thereby etching many metal workpieces.
According to the method of the present invention, as the above mentioned as many workpieces are etched with one stencil and without making of a resist pattern per a workpiece, the operation is simple and not only many complicated-shaped products of close tolerance can be quickly produced at a low cost but also the same etching can be applied even to a metal workpiece having a large area.